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To the Editor:—In our paper which appeared in the June 1936 issue of the Archives (Performance Characteristics of Electrical Hearing Aids for the Deaf, Arch. Otolaryng. 23:617, 1936) we gave the results of extensive tests which we made of four nationally advertised portable hearing aids of the carbon microphone type equipped with both air and bone conduction receivers. We carefully protected the manufacturers, who generously cooperated with us, from any possible unfavorable comparison of the merits of their respective products by designating by number the instruments tested, keeping their identity unrevealed.
In the advertising pages of the September 1937 issue and of several previous issues of the Revue de l'Ouie, a bimonthly organ of two national organizations for the hard of hearing in France, there appeared in the advertisement of the Companie Française des Microphones Acousticon, the French subsidiary of the Dictograph Products Company, Inc., of New York, the following